The term platform as used in a computer context can refer to the type of processor and/or other hardware on which a given operating system or application program runs, the type of operating system on a computer or the combination of the type of hardware and the type of operating system running on that hardware.
The terms cross-platform, multi-platform, or portable, can be used to describe operating systems and application programs that can run on more than one platform. Multi-platform operating systems can refer to operating systems that can be compiled or configured to run on multiple processor platforms. Multi-platform applications can refer to applications that can be compiled or configured to run on multiple processor platforms and/or multiple operating systems. Multi-platform software can be differentiated between platforms at compile time, while some software can perform runtime differentiation between platforms.
Applications or operating systems that are not multi-platform, in some instances, can be ported between platforms. Porting describes the development of a version of an application or an operating system originally designed for one platform such that the application or operating system can be used on other platforms. The portability of a software project can vary based on the differences between the origin and target platform. Porting a software project can involve changes to core program code, as well as libraries or applications associated with the program code.